Abstract: A method is illustrated for identifying which one of a plurality of signal transmitting spans in a communication network of signal spans, such as bundles or sets of DS3 signals, has been interrupted by some type of failure. This identification is based on a local level knowledge, as opposed to prior art network level knowledge, by monitoring each circuit in a given span for either a directly observable signal impairment, or an alarm indication signal (AIS) and sending an IDLE whenever a directly observable signal impairment or an alarm indication signal is detected and declaring that the channel immediately upstream from that node has failed when either the directly observable signal impairment or the alarm indication signal is received for longer than a predetermined period of time. Such a determination as to the whereabouts of a failed span can then be used for other processes such as implementation of a network restoration scheme.

Abstract: A method and system for multiple WDM signal compensation compensates optical chromatic dispersion for a plurality of optical signals having predetermined frequencies and each traveling in an optical path associated with the wavelength division multiplexer that forms a multiplex optical signal from the plurality of optical signals. The invention first undercompensates the multiplex optical signal by a predetermined amount so that each of the optical signals has an associated residual optical chromatic dispersion. Then, either before or after undercompensating of the multiplexed optical signal each of the optical signals is individually compensated to remove therefrom the residual chromatic dispersion. The system and method permit simultaneous and independent control of optical dispersion at any desired wavelength, as well as selection of matching compensation for optical transmitters prior to installation. The result is an increase in the usable wavelength range of optical signals for WDM networks.

Abstract: The present invention provides a method and system that compensate end-to-end optical dispersion for a fiber-optic cable having a plurality of predetermined compensations sites to within a predetermined dispersion limit using a predetermined dispersion compensation increment. With the method and system, the predetermined dispersion compensation increment may exceed both the predetermined compensation limit as well as the compensation limit divided by the number of sites. The method includes the steps of compensating optical dispersion using the compensation increment for each of the plurality of predetermined compensation sites to yield an end-to-end optical dispersion compensation within the predetermined optical dispersion limit. This may include optical dispersion over-compensation at some sites and optical dispersion under-compensation at other sites.

Abstract: A connector for connecting coaxial cable to a microstrip transmission line on a substrate is disclosed. The connector includes tapped threaded holes in a mounting plate, and an extended throat between the mounting plate and the threaded coaxial coupler. The threaded holes and extended throat allow for the mounting of the connector on the inner surface of the chassis wall, for example within a machined cavity or within a stamped dimple. The chassis bolt holes are oversized, to allow for fine adjustment of the vertical and lateral position of the connector on the chassis wall relative to the transmission line trace. The resulting connection has reduced UHF signal attenuation, and also a higher reliability connection to the transmission line.

Abstract: A system is illustrated that uses a spare or auxiliary add-drop muldem located at each end of N high capacity transport circuits to form a ring-type protection circuit using one additional high capacity transport. This is accomplished by using error detection circuitry to switch all of the auxiliary muldems to be normally in a high speed input/output circuit LOOPed condition but switching the auxiliary muldems on either end of a "bad" circuit to a THRU or open condition upon detection of a problem and allowing signals to be routed through the protection transport mechanism rather than the normal transport mechanism.

Abstract: In a skywave adaptable communication network, the time required to initiate communications between two transceivers can often be an important factor where the propagation characteristics of signals at various frequencies may bary drastically with time. The present invention not only improves upon known prior art by accepting the first frequency that it hears as a communication frequency when two nodes are attempting to communicate from a known list of probe frequencies to be transmitted at known times, it initially uses predictive frequencies in probe signal format during the time that would later be used for traffic information after link-up has occurred where the predictive frequencies may be based on algorithms, experience or whatever. Once link-up has occurred, the probe signals are used to allow the system to then adaptively change to better quality signals as these better quality signals are received, analyzed and compared with present working frequency signals.

Abstract: In a skywave adaptable communications network, the time required to initiate communications between two transceivers can often be an important factor where the propagation characteristics of signals at various frequencies vary drastically with time. The present invention improved upon the prior art by accepting the first frequency that it hears as a communication frequency when two nodes are attempting to communicate from a known list of frequencies to be transmitted at known times. The system then adaptively changes to better quality signals as these better quality signals are received, analyzed and compared with present working frequency signals.

Abstract: A snap fit cable retainer is illustrated for accommodating multiple diameter cables in a snug fit configuration by having the bit portion between adjacent side legs being closer to the extremities of the legs than is the main bit portion of the overall connector. In this way, large diameter cables can be run lengthwise through the retainer and smaller diameter cables can be run crosswise through the retainer. The retainer can also accommodate a layer of cables in each direction simultaneously by placing the lower level in the crosswise direction through the retainer and the second layer on top in the lengthwise direction.

Abstract: An integrated attitude director indicator and horizontal situation indicator is disclosed that utilizes stereopsis to combine information that normally requires two display surfaces onto a single electronic display. One embodiment of the display comprises left and right eye versions alternately presented on the display in synchronism with alternate eye shuttered lenses worn by the viewer. The viewer has an instantaneous sense of the real world direction from his aircraft as apparently suspended within a spherical grid. The integrated display provides a presentation somewhat similar to existing flat screen separate instruments with an aircraft symbol lying at the center of the sphere with roll, pitch and heading scales displayed on this sphere. The sphere itself has one color such as blue above the horizon line and a different color such as brown below the horizon line.

Abstract: A connector retainer is illustrated for use with at least two inline sets of right angle electrical connector pins whereby the connector retainer flexibly partially encloses and interlocks with the connector and has an extension thereof inserted in the right angle portion of the electrical pins wherein the inserted portion is of a larger diameter than the distance between the inline sets of pins. Such a portion can fit in the right angle portion between the sets of the pins and provide a hinge-type function without being able to move either horizontally or vertically thereby retaining the connector in contact with the electrical pins.

Abstract: A snap fit cable holder in a U-shape with two legs is shown with snap fit projections on both the inside and outside of the legs of the holder and at different relative heights with respect to the bit portion of the device. In this manner, the legs can be inserted through first and second openings to be held by their inside edges of the openings or can be inserted in first and third openings to be held by the outermost edges of the first and third openings. This allows a single cable connector to be used with at least two different size cables. Further variations may be obtained by adjusting the thickness of the support base containing the openings.

Abstract: A bandpass filter is used, which closely matches the characteristics of a closed phase lock loop (PLL) so as to provide an acquisition detector output in a PLL being swept. This detector is not activated by noise generated in the loop due to data or other perturbations. This filter includes a differentiator to exacerbate the filtered output and thus, more clearly define the condition being detected. The phase lock acquisition sweep is disabled when the detector output exceeds a predetermined absolute value. The detection scheme works equally well in approaching the lock frequency from above or below actual lock and a latch circuit ensures that the sweep approach always alternates to compensate for an erratic phase detector in the PLL.

Abstract: The present invention provides an approach to reconnect a communications network such as a DS3 telephone-type network when a span of DS3 channels is rendered inoperative, such as by cutting, within the 1.5 second time frame necessary to prevent disablement of local offices. This is accomplished by preplanning a restoration connection for each possible operating link failure in each span using spare capacity. A dedicated (DS3) communication loop is used to inform all nodes in the network substantially simultaneously to implement their portion of a plan associated with the failed span. After the restoration occurs for a given failed span, the concept can be extended to start planning for further failures or can be designed to restore further failures on a real time basis.

Abstract: A method is shown, along with apparatus for accomplishing same, for minimizing power required to keep an enclosed electronic module from overheating in a high temperature environment, while still operating to maintain the module at greater than a given minimum temperature when the environmental temperatures are far below the sensed minimum temperature for the module. This is accomplished by placing a thin sheet of heating material between the module to be temperature maintained and a heat sink which is exposed to the environment exterior the enclosure. Energy applied to the sandwiched heater prevents transfer of heat from the electronic module to the environment in such a way as to drastically reduce the heat (power consuming) requirements as compared to prior art heater approaches.

Abstract: Two pulse-width modulated power supplies are synchronized to operate at 180.degree. of phase shift to reduce the peak amplitude of the instantaneous current drawn from the DC input bus. The circuit includes means for disabling the synchronization upon detection of an undervoltage fault condition on the output of either supply. This feature allows frequency programming techniques to be used to provide foldback current limiting for either supply without affecting the operation of the other supply.

Abstract: Overvoltage and component failure protection for redundant current-mode controlled power supplies operating in parallel takes a supply off line when the supply drives the output bus to an overvoltage condition, without removing properly functioning supplies from the bus. The supply is also taken off line when either the error amplifier or the PWM fails.

Abstract: An algorithm is presented along with circuitry for implementing same to accomplish the interface of a pair of synchronized data lines with a pair of non-synchronized data lines using data buffers where there can be as few as three cells of data buffers to accomplish reading data out and writing data in without interfering one with the other. This algorithm is accomplished by measuring the time skew between overhead bits of the two non-syncrhonized data streams and writing to the frame most recently read by the synchronized data stream based on an algorithm formulated in view of or based on a function of the time skew.

Abstract: A low inductance shielded cable connector to printed circuit interface with an isolated chassis ground can be obtained by a multilayer printed circuit board and plated-through holes. Two or more layers of the printed circuit board are used to provide a capacitive connection to chassis ground and other layers are used to provide connections for signal ground (cable ground) and signal connector leads. The direct contact of the shielded cable connector to a multiplicity of points on the exterior layer of the printed circuit board, wherein the contact points completely encircle the signal conductor, substantially eliminates both radiation of signal and pickup of signals by the signal conductor.

Abstract: A laser signal coupling device one embodiment of which comprises a transmitter where a laser diode is coupled to a single mode fiber optic cable through the use of a lens whose position relative the diode is kept constant but whose length is adjusted to obtain a beam waist for the focused beam at some predefined point such as inside the end of the fiber optic cable. Such a positioning of the beam waist can increase the yield by reducing the effect of alignment variations in axial, radial and angular directions as well as reduce noise from fiber end surface reflections. The same concept may be used to accurately focus signaling received from an optic cable, in a surface of a signal detector. Further, the concept may be used for focusing between optic cable of different types such as converting from multi-mode to single-mode fiber optic cable.

Abstract: The present disclosure illustrates that the process of summing an amplitude limited PSK (phase-shift keyed) signal with a one data bit delayed version of that signal and envelope detecting the sum will produce a digital binary data stream that is representative of the original data used to produce the PSK signal in the first place. This approach is distinguished over the prior art approach in that the PSK signal is limited to an amplitude value which is less than the minimum value produced by vectorial summation of noise with the transmitted PSK signal for optimal bit error rate performance.